Any time a booted computer spontaneously reboots or blue-screens, that is bad for your hard-drive data. It tends to cause corruption and stranded temp files, which hog little bits of space.
The problem is caused by a driver. it's not necessarily that the driver is written wrong, it may be that you've got file corruption that's getting worse over time, and now a particular driver is unable to load into memory in a useful way.
It would help for you to know which driver, like patonb said, but if the problem is being caused by corruption, then you might have thousands of corrupted files, getting worse every day.
You should check your memory first, again like patonb said.
Then run CHKDSK /R. If that won't run, try CHKDSK /F first, then try CHKDSK /R again. You should check your physical memory first because if you memory is bad, then running CHKDSK through bad memory could lead to even more corruption, instead of fixing corruption.
It is possible that corruption has occurred that CHKDSK can't fix. In that case, you should uninstall and reinstall and/or update every driver you can, starting with motherboard drivers.
Laborious, I know, but probably the only way.
Hopefully the corruption isn't being caused by a failing hard drive. A failing hard drive tends to log lots of System errors: Event 7. If these are pointing at a DVD, CD, or USB, don't worry. If they point at a hard drive partition, then that says you have corruption, and may or may not be fixed with CHKDSK. So if you have Event 7 errors, and you run CHKDSK, clear the logs. Then monitor the logs to see if Event 7's come back. That would indicate that maybe you need to replace your hard drive before it dies.
Also, MemTest is a great utility. However, once i ran extensive memory tests that all came up good, but i just couldn't figure out what the problem was. since i had extra memory, I swapped it anyways. That fixed it. Some problems are intermittent, and a memory tester might still be unable to detect a problem.
If you don't have extra memory, another thing to try is to swap your memory sticks. If you have two sticks, reverse which slots they're in. If it takes longer to end up with the same problem, then you could suspect one of the sticks.
Hope this gives you a practical list of things to try.